ON THE ROLE OF TANNIN VACUOLES IN SEVERAL NASTIC LEAF RESPONSES

Experiments were done to relate the presence of tannin vacuoles to pla nt movements. When surveyed, 4 our of 10 species exhibited rapid thigm onastic or nyctinastic movements, and only those 4 species had tannin vacuoles in their motor cells. Interestingly, plants of Albizzia julib rissin whose seed was obtained in New Haven, Connecticut had rapid nyc tinasty and tannin vacuoles in the tertiary pulvini, whereas Albizzia collected in Winston-Salem, North Carolina had neither. Nyctinasty of Mimosa pudica and Albizzia NH, both of which had tannin vacuoles, was at the rate of 4.2 degrees/min, whereas Albizzia WS and Samanea saman, neither of which had tannin vacuoles, exhibited leaflet closure at th e rate of 2.0-2.1 degrees/min. Pretreatment with the Ca2+ channel agon ist Bay K-8644 increased, and with the antagonist verapamil decreased, the rate of leaflet closure only in Mimosa and Albizzia NH. Pretreatm ent with the Ca2+ inhibitor Erythrosin B substantially blocked reopeni ng only in Mimosa and Albizzia NH. We conclude that tannin vacuoles as sist nastic movements to be rapid by acting as a store of Ca2+ and rel easing it as a second messenger upon mechanical perturbation or darkne ss.